Due to many advantages, such as high voltage, small size, light weight, high specific capacity, no memory effect, no pollution, low self-discharge, long cycle life and the like, a lithium-ion battery has been unprecedentedly developed during applications in many fields, including the fields of telecommunications, electric appliances, electronic information, and power equipment, energy storage and the like. However, with the rapid development of society, these applications have increasingly higher requirements for energy density, charge and discharge rates, cycle life of the lithium-ion battery, and at the same time, it also requires that the lithium-ion battery has a reliable safety performance.
There are many factors which have an influence on the safety performance of the lithium-ion battery. Positive and negative electrode materials, an electrolyte and its additives, and a structure and preparation process conditions of the lithium-ion battery have a significant influence on the safety performance of the lithium-ion battery. The thermal stability of the lithium-ion battery can be improved by selecting the positive and negative electrode materials, the electrolyte and its flame retardant which have good thermal stability; an overcharge protection additive is added in the electrolyte, which can effectively improve an overcharge performance of the lithium-ion battery; short-circuiting of the lithium-ion battery can be reduced by well-controlled preparation process conditions and reasonable use.
However, increasingly severe safety test conditions of the lithium-ion battery put forward higher requirements on the safety performance of the lithium-ion battery. For example, a drop test, a tumbling test and the like put forward more severe requirements on appearance and internal short-circuiting and the like of the lithium-ion battery. Some conventional improved methods are often unable to meet the new test conditions, and difficulty and technical cost for continuing to improve the conventional material systems and preparation process are also greatly increased. Therefore, it is necessary to provide a lithium-ion battery which effectively meets the severe safety test requirements at present, while the process operation is simple, the cost is low, and it is easy to realize.